Photographic developer



United States Patent PHOTOGRAPHIC DEVELOPER Robert 0. Mease, Roiling Hills, Calif assignor to Records Service Corporation, Los Angeles, Calif., a corporation of California No Drawing. Application May 10, 1954,

Serial No. 428,838

5 Claims. (CI. 96-66) This invention relates to photographic developers for developing photographic film, print paper and other photosensitive surfaces having silver halide emulsions.

The object of the invention is to provide a rapid developer, i. e., one which will develop a silver halide-bearing coating in a length of time which is greatly reduced from that required in the use of conventional developers now available. For example, the invention provides for fully developing in five seconds a film emulsion now requiring from four minutes to twenty minutes for development, and a print paper emulsion now requiring from thirty seconds to two minutes for development.

A further object of the invention is to provide a developer having hypersensitizing qualities, i. e., the ability to increase the speed (sensitivity) of some emulsions up to ten times their normal speed.

Another object is to provide a developer having a wide temperature tolerance, i. e., which is capable of being used successfully in operating temperatures over a much wider range than that within which conventional developers are limited for successful operation. For example, whereas most conventional developers are used within a temperature range of from 68 to 75 for satisfactory results, the developer of my invention can be used through a range extending beyond both limits of said range of conventional developers, i. e., from 58 up to 85 F. and higher.

The invention deals with ingredients which are largely conventional, i. e. ingredients already in use in well known developers, but uses these ingredients in diiferent proportions and utilizes a novel formulation in the assembling of the ingredients to produce the developer. The extra-ordinary results obtained by the invention are believed to be due to these departures in proportioning and formulation of materials.

The invention is particularly useful in connection with developing records which are produced in long rolls of exposed film or print paper such as oscillographic records (oscillograms), film exposed in military aerial photography, or other records which may call for development in as short a time as possible after exposure; or in other commercial developing operations; where, in order to reduce the cost of developing a high footage of film or print record, it may be highly desirable to attain development in a rapid passage of the sensitized strip through a developer.

Accordingly another object of the invention is to provide a developer paticularly suitable for such high volume military or commercial operations involving high footage of roll film or sensitized ribbon, for development.

Another object is to provide a developer which is capable of being used in developing a relatively large area of emulsion surface (as contrasted to the capacity of commercial developers now available) without a reduction in developer strength below a minimum requirement.

A further object is to provide a developer which may be kept for long periods of time in liquid form without having its strength orquality impaired.

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Other objects of the invention will become apparent in the following detailed description of the invention.

The developer of my invention utilizes two aqueous solutions, which for convenience in referring to them will be designated Solution A and Solution B respectively. Solution A may be regarded as the basic developer solution and Solution B as an additive to be mixed with Solution A to formulate the complete developer solution, ready for use. Each of the solutions is preferably compounded in concentrated form i. e., as a concentrate embodying a minimum quantity of water to dissolve the other ingredients and each calling for dilution by additional water prior to use.

7 SOLUTION A Solution A utilizes, in addition to water, simply the three ingredients, sodium sulphite, NazSOs; Metol,

HOCsH4(NHCH3) /2H2SO4 also known by the name Elon and other names; and hydroquinone CeH4(OH)2 or p-dihydroxybenzene. The function of these three ingredients, in general, is the same as in conventional developers utilizing them, i. e., the Metol and hydroquinone function as the active developing agents for reducing the activated silver halide grains, and the sodium sulphite functions as an agent to inhibit oxidation of the developing agents. However, the effective action of these ingredients is characterized by the greatly increased rapidity of developing action hereinbefore referred to, a result which is ascribed to the following facts:

(a) Additional ingredients used in other developers are omitted. For example, the Eastman high-contrast Kodak D-l9 stock solution contains sodium carbonate and potassium bromide, which are not utilized in the developer of my invention, and the Eastman low-contrast (Kodak D-76) developer contains borax which is not utilized in my developer.

(b) The proportioning of ingredients is different from that in existing commercial developers utilizing the three ingredients mentioned above. For example, in the Kodak D-19 high contrast solution, the quantitatively predominant ingredient is sodium sulphite, and only relatively small proportions of hydroquinone and Metol are utilized, the total of the latter two ingredients being less than one eighth of the total of the three ingredients, whereas in my developer, the sodium sulphite is only a minor proportion of the total, being three percent or less.

(c) In the formulation of my developer, the ingredients are added to one another in the following order:

1. Water for dissolving 2. Sodium sulphite 3. Metol 4. Hydroquinone.

Metol1l grams plus or minus about 1.6 grams Hydroquinone-ZZ grams plus or minus about 3.3 grams.

Stated diiferently, a solution containing between /2 and 1 gram of sodium sulphite may contain from about 9 to about 13 grams of Metol and from about 18 to about 25 grams of hydroquinone, the ratio of approximately 1:2 as between the Metol and hydroquinone, being observed,

In each ofthe instances mentioned above, they ingredients are addeitogan initial quantity of 7400 grams...

more fully the range ofv proportioningwithin which solution A of thisinventionmay fall: 7

Example A1.Optimum V Water for s luti n V Sodium'sulphite grams 1 Metol do ll Hydroquinone do 22 Water to make 500 V 7 Example A-2 7 Water for solution cc 400 Sodium sulphite grams 1 Metol do 9 Hydroquinone ..do 18 Water to make; cc 500 Example A-3- Water for solution"; cc 400 Sodium sulphite grams 1 Metol do 13 Hydroquinone do 25 Water to make cc 500 Example A-4 Water for solution cc 400 Sodium sulphite grams A2 Metol do 1 1 Hydroquinone do 22 In the examples given, Where the proportions of Metol and hydroquinone vary 15% more or less than the respective quantities 11 grams and 22 grams, the values of one gram and one half gram given for the sodium sulphite are the respective upper and lower limits for that material. More specifically, the one gram and one-half gram values for sodium sulphite actually constitute the upper and lower limits of that material for the values of 11 grams and 22 grams of Metol and hydroquinone respectively.

in all examples given above, the quantity of 400 cc. of initial water for solution is the minimum for approximately saturation in the concentrated solution.

The following additional examples of proportioning which produce the characteristics of the invention, are given:

Example A-5 Water for solution cc 400 Sodium sulphite grams 1 Metol 13 Hydroquinone do 22 Water to make cc 500 Example A6 Water for solution cc 400 Sodium sulphite grams 1 Metol do Hydroquinone do Water to make cc 500 Example A-7 Water for solution cc 400 Sodium sulphite grams 1 Mctol do 11 Hydroquinone do Water to make cc 500 Example A-8 Water for solution cc 400 Sodium sulphite grams /2 V MCtOl (in 9 Hydroquinone Q. do-

4 SOLUTION B Solution B is added to Solution A immediately preceding the use of the developer solution. Solution B contains, in addition to water, the two active ingredients sodium sulphite and sodium hydroxide. As in the case of Solution A, the water includes an initial quantity of Water for solution and a subsequent quantity of Water to make.

. tions having been preserved in the concentrate form up to the point of use. 7

As in Solution A, fairly narrow ranges of proportioning are observed; the range for sodium hydroxide being plus or minus 15% variation for a fixed amount of sodium sulphite and the range for sodium sulphite. being somewhat greater, i. e. plus or'minus 25% variation for a fixed amount of sodium'hydroxide. V V

In the concentrate solutionutilizing 400 cc. of'water for solution, the amounts of the respective active ingredients are: sodium sulphitegrams plus or minus about 18 grams and sodium hydroxide 35 grams plus or minus about 5 grams; Water tomake 500 cc. is later added.

At this point, it may be noted that the unit quantity just given is the quantity that is mached to the unit quantity for solution A, which also contains 400 cc. of water for initial solution and water to make 500 cc. is later added. In the mixing of thetwo solutions for the complete developer, the two unit quantities as illustrated above will be mixed in the proportion of 1:1.

The following examples are given to illustrate the range of proportioning for Solution B which attains the characteristics of the invention:

For the optimum conditions, the ratio of sulphite to hydroxide is 2:1.

Example B-Z Water for solution l cc 400 Sodium sulphite grams 70 Sodium hydroxide do 40 Water to make cc 500 Example B-3 7 Water for solution cc 400 Sodium sulphite grams 70 Sodium hydr x do 30 Water to make cc 500 Example B-4 Water for solution cc 400' Sodium sulphite grams 88 Sodium hydroxide do 35 Water to make cc 500 7 Example. B-5

Water for solution cc 400 Sodium sulphite; grams 52 Sodium hydroxide do 35 Water to make cc 500 The quantities for sodium sulphite ingredient in each of the solutions A and B, are correct where the sodium sulphite is desiccated or completely anhydrous; i. e. for

the quantities given,'the inventioncontemplates the-use.

of desiccated sodium sulphite.

quantities given in the examples above, with the water to make (2 parts, one part for each of the solutions) For optimum developing speed (minimum. time interval) equal parts of Solutions A and B are utibeing added just before use. This mixture, without additional water, is used for optimum results in the development of film. For the development of print paper, it is desirable to add a further quantity of the water to make" to the extent of an additional 1000 cc. to the sum of 500 cc. plus 500 cc. for the two unit volumes of solutions, so that the total unit volume for the mixture would be 2000 cc.

SPECIAL FIXING SOLUTION The invention contemplates the use of a particular hypo or fixing solution in connection with the fixing of photosensitive surfaces developed by the use of my improved developer. This fixing solution includes, for a unit volume proportioned to the unit volumes for the developer, as given above, a combination of the following ingredients:

Example I .Optimum Water for solution cc 400 Ammonium thiosulphate (active ingredient) grams 700 Sodium sulphite do 24 Glacial acetic acid cc 18 Boric acid grams Aluminum chloride do 14 Water to make cc 500 As in the developer, the range for the respective ingredients is fairly narrow, extending above and below the respective quantities given above, as follows:

The term glacial acetic acid is used to refer to an acetic acid from which water has been eliminated by freezing.

The water content in each case remains constant; i. e. the range of deviation given above is applicable to a fixed Water content as given.

In the above formula, the ammonium thiosulphite is the active fixing ingredient. The sodium sulphite is also a preservative. The acetic acid is a neutralizer and buffer. The boric acid is likewise a buffer. The aluminum chloride is a hardening agent.

This fixing solution differs from conventional fixing solutions in utilizing aluminum chloride, which is not used in conventional hypos, and in utilizing ammonium thiosulphate instead of the sodium thiosulphate commonly used in hypos. My special fixing solution also differs from conventional hypos in having a diiferent proportioning of ingredients. For example, a much higher percentage of ammonium thiosulphate is used in my hypos as do utilize this ingredient.

The following improved results are obtained by the use of this improved hypo:

1. It is much faster in fixing time, making it possible to reduce normal fixing time by at least 33 /s%.

2. It has a much longer life than conventional fixing solutions; i. e. it maintains its fixing strength through a much greater volume of use (much greater area of fixed photosensitive surface) than conventional hypos.

I claim:

1. In a developer for silver-halide-emulsion-bearing surfaces, the combination of the following ingredients in approximately the following optimum proportions for mixing with water to make a total volume of 1000 cc. of developer ready for use: water for solution800 cc.; sodium sulphite 71 grams; sodium hydroxide-35 grams; Metol11 grams; hydroquinone-22 grams.

2. In a developer for silver-halide-emulsion-bearing surfaces, the combination of the following ingredients in approximately the following optimum proportions for mixing with water to make a total volume of 1000 cc. of developer ready for use: water for solution-about 800 cc.; sodium sulphite-between 53 grams minimum and 89 grams maximum; sodium hydroxide-between 30 grams minimum and 40 grams maximum; hydroquinone between 18.7 grams and 25.5 grams; Metolbetween 9.4 grams minimum and 12.6 grams maximum, approximately a 1:2 ratio between the amounts of Metol and hydroquinone respectively, being maintained.

3. In a developer for silver-halide-emulsion-beating surfaces, the combination of the following ingredients in approximately the following optimum range of proportions for mixing with water to make a total volume of 1000 cc. of developer ready for use: water for solutionabout 800 cc.; sodium sulphitebetween 52 /2 grams and 89 grams; sodium hydroxide--between 30 and 40 grams; Metolbetween 9.4 grams and 12.6 grams; hydroquinonebetween 18.7 grams and 25.5 grams.

4. In a developer for silver-halide-emulsion-bearing surfaces, the combination of the following ingredients in the following optimum range of proportions, for a volume of 1000 cc. of solution by the addition of water to make a developer ready or use: sodium sulphitebetween 52 /2 and 89 grams; sodium hydroxidebetween 30 and 40 grams; Metolbetween 9.4 grams and 12.6 grams; hydroquinonebetween 18.7 grams and 25.5 grams.

5. In a developer for silver-halide-emulsion-bearing surfaces, the combination of the following ingredients in,

the following optimum proportions, for a volume of 1000 cc. of solution by the addition of water to make a developer ready for use: sodium su1phite71 grams; sodium hydroxide.40 grams; Metol13 grams; hydroquinone-25 grams.

References Cited in the file of this patent OTHER REFERENCES 7 Clerc: Photography, Theory and Practice, Pitman,

New York, N. Y., 2nd ed., 1937 pp. 263-264. (Copy in Div. 67.)

Henney et al.: Handbook of Photography, McGraw-' Hill, New York, N. Y., 1939, p. 373. (Copy in Div. 67.) Photographic Journal, Sec. b, vol. 87 B, 1947, page 110. Neblette: Photography, Von Nostrand, New York,

N. Y., 5th ed. 1952, pp. 339-340. 

1. IN A DEVELOPER FOR SILVER-HALIDE-EMULSION-BEARING SURFACES, THE COMBINATION OF THE FOLLOWING INGREDIENTS IN APPROXIMATELY THE FOLLOWING OPTIMUM PROPORTIONS FOR MIXING WITH WATER TO MAKE A TOTAL VOLUME OF 1000 CC. OF DEVELOPER READY FOR USE: WATER FOR SOLUTION-800 CC.; SODIUM SULPHITE-71 GRAMS; SODIUM HYDROXIDE-35 GRAMS; METOL-11 GRAMS; HYDROQUINONE-22 GRAMS. 